Hi every one, I recently overlayed 3/8" sheetrock over the existing ceiling that had painted swirl finish. I used paper tape on the outside perimeter inside corners and used mesh tape along the seams and butt joints. When applying my final coats of lightweight joint compound that there was a slight hairline crack along the butt joints of the first two sections of sheetrock, so I applied more compound and again saw there is a slight crack along the joint. If I push up against the drywall the crack dissappears because it is hanging down ever so slightly. Should I remove the mud with water and a spounge along the joint and tape with paper and remud? Or should I go in the attic and piece in 2x6 between the joists so I have something to screw into along butt joint and then screw and finally mud over?